Question

Two parallel rail tracks run north-south. Train a moves due north with a speed of 54 km h-1 and train b moves due south with a speed of 90 km h-1. What is the relative velocity of b with respect to a in m s-1?

Answer 1

Answer:

The relative velocity of b with respect to a is  40 m/s

Explanation:

Train a moves to north with the speed say s(a)=  54 km /h

Train b moves to south with the speed say s(b)=  90 km /h

Therefore the relative velocity of b with respect to a=

s(b)-s(a)

= -90-54

= 144 km/h

now to convert km/h to m/s

144km/h x 1000m/1 km x 1 h/3600s

= 40 m /s